This is a competing renewal of a Training Program whose main objective is to prepare highly qualified post-doctoral fellows for a basic research-oriented career in academic medicine pertaining to Respiratory Physiology and Biology, in health and disease. In this Program, we will encourage applications of MD and PhD candidates from various sources (Clinical & Basic Science Departments) emphasizing a nationwide competition. To maximize the impact of this Training Grant, MD trainees are allowed to enter this program only after having completed the clinical requirements for Board eligibility and having experienced bench-investigation. Optimal research training is achieved by protecting trainees' time and 95% of the trainees' efforts will be dedicated to research in this Program. Training is preceptor-based and is enriched by didactic courses given before and/or during the research training period and by interactions with a broadly-based resource faculty. This faculty was chosen with great cased based on on-going research productivity, significant extramural support and availability and commitment to serve as mentors. They also belong to 3 research sphere identified as important in respiratory disease processes: epithelial cell biology and transport, immunobiology and inflammation and neurobiology and sleep. Because of the wide spectrum of available strong laboratories in the Yale environment and the institutional nature of this proposal, eight post-doctoral positions are requested per year. The duration of the Program will be a minimum of 2 years and we anticipate that there will be, on average, 1 trainee who will require an additional third year. Trainee progress will be carefully evaluated and productivity monitored by each mentor, the Program Director and an Executive committee. The uniqueness of this Program stems from a) the truly institutional nature of this Grant involving 2 Clinical Departments (Pediatrics and Internal Medicine) and 8 Basic Science Departments; b) the strong interactions that exist between the Clinical and Basic Sciences faculty on this Program and between this resource faculty and the faculty of the Boyer Center for Molecular Medicine and the Howard Hughes Institute at the School of Medicine and c) the training track record of the resource faculty. Through this Program, we expect to entice, train, and prepare future leaders in pulmonary research in academic pediatrics, internal medicine and basic science arenas.